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The potential of using two natural polymers (chitosan and shellac) for the formation of nanoparticles by the process of ionic cross-linking to encapsulate bovine serum albumin, a model protein was investigated. Depending on the concentrations of chitosan, shellac and bovine serum albumin, three physical states - nanoparticle, aggregation, and solution could be observed as a result of the electrostatic force. The formation of nanoparticles was due to the balance between the repulsion force and attractive force while the imbalance between both forces resulted in the formation of aggregation and solution. The Fourier transform infrared spectroscopy and differential scanning calorimetry were applied to prove the nanoparticle formation. The particle size was characterized by the light scattering technique and was found in the range between 100 and 300 nm. The morphology of the particles, detected by transmission electron microscopy was spherical shape. The result showed that the zeta potential of the nanoparticles possessed positive charges. The concentrations of chitosan, shellac and bovine serum albumin had an influence on the physicochemical properties of the nanoparticles such as the particle size, the zeta potential, the encapsulation, the loading efficiencies and the cumulative release. Therefore, chitosan and shellac could be used to form nanoparticles for protein delivery by the ionic cross-linking method.

The objectives of this study were to prepare the hydroxypropyl methylcellulose (HPMC)/polycarbophil (PC) mucoadhesive blend film and to investigate the main and interaction effect of HPMC and PC mixtures on the physicochemical and mechanical properties of blend films using a simplex lattice mixture design approach. The cubic and quadratic models were selected to analyze mucoadhesive properties in terms of work of adhesion and maximum detachment force, respectively. It was shown that HPMC/PC blend film had higher mucoadhesive properties than pure HPMC film. The suitable models for analyzing swelling index of blend films at various times were assessed. The puncture strength, % elongation and hydrophilicity of films were also examined. The pure HPMC film displayed more homogeneous and smoother structures compared with the blend film, as observed by scanning electron microscope and atomic force microscopy. Intermolecular hydrogen bonding between HPMC and PC was detected using Fourier transform infrared and X-ray diffraction. Therefore, the blend film shows high potential for use as a buccal delivery system. Key words hydroxypropyl methylcellulose (HPMC); polycarbophil; blend film; mixture design; mucoadhesive film; buccal drug delivery Buccal drug delivery systems have several advantages such as good accessibility, avoiding hepatic first pass metabolism and drug degradation in the gastrointestinal tract.

Herein, thermosensitive blends of poloxamer 407 (P407)/poloxamer 188 (P188)/polycarbophil (PCB) were developed in terms of maximized content of PCB (a mucoadhesive polymer) and desired temperature-dependent rheological properties of the blends as in situ gelling matrices. Maximizing PCB content while achieving the preferable rheological characteristics was accomplished through the Box–Behnken design. The quantitative effect of the polymer composition in the blends on the thermosensitive characteristics was evaluated using the fitted design model and the corresponding surface plots. The optimized P407/P188/PCB blend (OPT) was the mixture of 20.000, 7.349 and 0.595% (w/w) of P407, P188, and PCB, respectively. The thermosensitive micellization of OPT was investigated using differential scanning calorimetry which revealed an overlapping double endothermic peak caused by the temperature-induced micellization of pure micelles in co-existence with the micelles with attached PCB. Mixing PCB with the P407/P188 matrix promoted a more intense mucoadhesion of the blend. After incorporating metronidazole, a model hydrophilic drug, into OPT, the temperature-dependent characteristics of the hydrogel did not change. Metronidazole release from OPT was sustained by an anomalous mechanism. This optimal ternary hydrogel benefiting from thermosensitive gelling and mucoadhesive matrix might be used as a viable platform for mucoadhesive in situ gelling drug delivery.